Extend texture to different objects
Select the object to unwrap, and while in edit mode press  U  to unwrap. Then, select the image you want to UV map to your objects from the list of available images (if more than one has been added to your scene), while in the UV/ image editor. Repeat for your other objects. In the attached gif, I just used a stack of cubes for simplicity, but the method should work in any case.